This invention relates to a device for detecting and quantitatively measuring the quantity of a select gas in a gaseous medium. More particularly, the invention relates to a device which is compact, dependable, easy to operate, and relatively inexpensive for detecting and quantitatively measuring a gas such as carbon monoxide, hydrocarbons or an alcohol in an environment. The device includes intake means, means for pumping the gas being analyzed, and an electrochemical cell for detecting and quantitatively measuring a select gas. Although the invention is not limited thereto, for convenience it will be described with reference to a device for detecting and measuring the alcoholic content in the breath of a test subject or for detecting and measuring carbon monoxide in a given environment. As will be apparent, however, the device can be modified or adapted for detecting and measuring hydrocarbons including separation of saturated and unsaturated hydrocarbons, gases capable of being converted to alcohols, carbon monoxide, or hydrocarbons, or other gases which can be electro-chemically consumed, where similar conditions apply.